Cutting blade for medical devices

ABSTRACT

An athertome assembly comprises a series of spanning and descending members extended between a segmented base and a cutting surface. This athertome assembly configuration provides both flexibility and structural strength which facilitates the implantation of medical devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable

FIELD OF THE INVENTION

In some embodiments this invention relates to implantable medicaldevices, their manufacture, and methods of use in particular atherectomydevices.

DESCRIPTION OF THE RELATED ART

Stents, grafts, stent-grafts, vena cava filters, expandable frameworks,and similar implantable medical devices are radially expandableendoprostheses which are typically intravascular implants capable ofbeing implanted transluminally and enlarged radially after beingintroduced percutaneously. These endoprostheses may be implanted in avariety of body lumens or vessels such as within the vascular system,urinary tracts, bile ducts, fallopian tubes, coronary vessels, secondaryvessels, etc. Some endoprostheses such as stents may be used toreinforce body vessels and to prevent restenosis following angioplastyin the vascular system. Endoprostheses may be self-expanding, expandedby an internal radial force, such as when mounted on a balloon, or acombination of self-expanding and balloon expandable (hybridexpandable).

Insertion of an implantable medical device can be facilitated by theattachment of one or more cutting tools to the radially compresseddevice. These tools, frequently called atherectomy devices orathertomes, typically comprise a blade, cutting bit, burr, and/or othersurface protrusions on at least a portion of the flexible drive shaft,catheter, or stent. Athertomes can be contained within flexible sheathsto protect the walls of the blood vessels from the rotation of theimplantable medical device. Athertomes can be attached to medicaldevices including but not limited to stents, balloons, grafts,catheters, and sheaths. Examples of such devices include Barath, U.S.Pat. No. 5,196,024, Shiber, U.S. Pat. No. 4,842,579, Simpson et al.,U.S. Pat. No. 5,047,040; and Auth et al., U.S. Pat. No. 5,314,407,incorporated herein by reference. The atherectomy device is typicallynavigated to the site of the disease by a delivery system such as amechanically manipulated guide wire to the site of the disease, and thenthe atheretome is advanced over the guide wire to the site.

The navigation of the guide wire through the blood vessel can be a slowand tedious process, requiring great skill. It can be difficult toprecisely control the atherectomy device satisfactorily. Part of thisdifficulty arises from rigidity of the blades which do not bend asreadily as balloons, stents, wires and other components of implantabledevices when traversing the wending paths of body vessels.

The art referred to and/or described above is not intended to constitutean admission that any patent, publication or other information referredto herein is “prior art” with respect to this invention. In addition,this section should not be construed to mean that a search has been madeor that no other pertinent information as defined in 37 C.F.R. §1.56(a)exists.

All US patents and applications and all other published documentsmentioned anywhere in this application are incorporated herein byreference in their entirety.

Without limiting the scope of the invention a brief summary of some ofthe claimed embodiments of the invention is set forth below. Additionaldetails of the summarized embodiments of the invention and/or additionalembodiments of the invention may be found in the Detailed Description ofthe Invention below.

A brief abstract of the technical disclosure in the specification isprovided as well only for the purposes of complying with 37 C.F.R. 1.72.The abstract is not intended to be used for interpreting the scope ofthe claims.

BRIEF SUMMARY OF THE INVENTION

At least one possible embodiment of the invention is directed to anathertome assembly comprising at least one segment having at least onebase member and at least one cutting member in which the cutting memberhas a first and a second side, at least a portion of the first sidehaving a cutting surface. The at least one segment also has at least onedescending member and at least one spanning member which at leastpartially define a through hole located between the at least onedescending member and the at least one spanning member. The at least onespanning member is engaged at one end to the second side of the at leastone cutting member and engaged at another end to the at least one basemember. The at least one descending member is engaged at one end to thesecond side of the at least one cutting member and extends in thedirection of the at least one base member but is not engaged to the atleast one base member.

The athertome assembly can be constructed in a number of variations.These variations include having a plurality of descending members,having a plurality of spanning members, having uninterrupted cuttingsurfaces, having non-adjacent base members, and having narrow connectorslinking adjacent members. The connectors themselves can be positioned invarious ways including at the center of a horizontal members.

At least some possible embodiments of the invention are directed to amedical system having at least one athertome assembly engaged to atleast one medical device. In some instances, the athertome assembly maybe disposed on the medical device such that an imaginary planeperpendicular to the central longitudinal axis of the medical devicepasses through a cutting member, a base member and a descending memberof the athertome. Appropriate medical devices include but are notlimited to stents, catheters, balloons, sheaths, grafts, andcombinations of these devices. The athertome assembly can be engaged toa medical device in a variety of ways including the following: Multipleathertomes assemblies can be engaged to a medical device. In somepossible embodiments three or four athertome assemblies will be engagedto a medical device. The multiple athertome assemblies can be located atpositions substantially equidistant from each other or innon-symmetrical relative positions. They can also be positioned atdifferent locations relative to the terminal end of the medical device.They can extend along the surface of a medical device along a number ofpaths including longitudinal, perpendicular, and diagonal paths. They orportions of them can have cutting surfaces positioned at differingdistances from the surface of medical device. They can be non-linearand/or can coil around the medical device in a helical direction. Inaddition, they can be flexibly engaged to the medical device and canpivot and change the angle they form with the medical device.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

A detailed description of the invention is hereafter described withspecific reference being made to the drawings.

FIG. 1 is a view of an athertome having unconnected base members.

FIG. 2 is a view of an athertome assembly having an athertome connectedto the outer surface of a medical device.

FIG. 3 is a view of an athertome having descending members connected tothe base member by connectors.

FIG. 4 is a view of an athertome having horizontal members connectingdescending members.

FIG. 5 is a perspective view of a catheter having four athertomesengaged to it.

FIG. 6 is a perspective view of an athertome assembly including ahelically arranged athertome.

DETAILED DESCRIPTION OF THE INVENTION

While this invention may be embodied in many different forms, there aredescribed in detail herein specific embodiments of the invention. Thisdescription is an exemplification of the principles of the invention andis not intended to limit the invention to the particular embodimentsillustrated.

For the purposes of this disclosure, like reference numerals in thefigures shall refer to like features unless otherwise indicated.

Depicted in the figures are various aspects of the invention. Elementsdepicted in one figure may be combined with, and/or substituted for,elements depicted in another figure as desired.

Referring now to FIG. 1 there is shown an athertome 2 having a first end27 and a second end 28 made up of a plurality of segments. Each segmentis made up of a cutting member 7 which is opposite one or more basemembers 11. The cutting member 7 has two sides, an inner side 18 whichis engaged to other athertome members and cutting side 19. At least aportion of the cutting side 19 defines the cutting surface 21 of theathertome 2. Extending between the cutting member 7 and the base members11 are crossing members 10, some of which are descending members 9 whichdo not reach all the way to the base members 11 and some of which arespanning members 15 which reach and are engaged to the base members 11.Separating the descending members 9 and spanning members 15 are throughholes 14. The through holes 14 are apertures extending completely thoughthe athertome material. Although in this illustration, the cuttingmember 7 and the base members 11 are parallel with each other this neednot be the case. This invention encompasses embodiments having anathertome 2 of any conceivable shape including but not limited tosquare, rectangular, triangular, rhomboid, etc. Similarly, some or allof the crossing members 10 need not be perpendicular to the base 11 orcutting members 7 and can be oriented at any oblique angle relative tothe base 11 or cutting members 7. This invention also encompassespossible embodiments where at least a portion of members other than thecutting member 7 can also have cutting surfaces. Although FIG. 1illustrates an athertome where spanning members 15 define the two endsof the athertome 2, this invention encompasses possible embodimentswhere the ends are defined by other members or features of the athertome2. In addition this athertome 2 encompasses possible embodiments wherethe first and second ends 27, 28 also have cutting surfaces.

In the embodiment shown, the cutting members 7 of each segment are allinterconnected and form one continuous and uninterrupted cutting member7 extending along the length of the athertome 2. In the embodiment shownin FIG. 1, the base of the athertome is not a single structure, but isinstead a series of base members 11 with base gaps 6 between each basemember. The embodiment also features descending gaps 3 between everyother descending member 9 and a base member 11. As with the throughholes 14, the base gaps 6 and the descending gaps 3 are aperturesextending completely through the material of the athertome 2. Thepresence of the base gaps 6 and the descending gaps 3 facilitatesflexing and bending of the athertome 2 relative to the medical device itis engaged to. This flexibility in turn facilitates the advancement ofthe delivery system carrying the medical device and the athertomeassembly 1 through the tortuous confines of a body vessel or otherlumen. This invention also encompasses embodiments where only a portionof the athertome 2 or only one segment has a continuous anduninterrupted cutting surface or only a portion of the athertome 2 hasbase gaps 6 and descending gaps 3.

An illustration of one possible embodiment where the athertome 2 of FIG.1 is engaged to a medical device 5 by the base members 11 is shown inFIG. 2. The types of medical devices capable of supporting mountedathertomes include but are not limited to stents, sheaths, grafts,shafts, catheters, balloons or any combination of medical devices. Theathertome can be a separate part attached to a portion of a medicaldevice or it can be an integrated component of the device created out ofthe same material as the medical device. Although FIG. 2 shows theathertome 2 located relatively close to the terminal end 26 of themedical device 5, this invention encompasses embodiments where theathertome 2 is located anywhere along the medical device 5.

Similarly, although this illustration shows a single athertome 2attached to the medical device 5, any number of athertomes 2 may be apart of, may be engaged to, or may protrude from an implantable medicaldevice. In at least one possible embodiment for example, at least threeor four athertomes 2 are radially affixed or otherwise engaged to amedical device such as a balloon or an implantable stent. The radiallypositioned athertomes can be equidistant to each other relative to thecircumferential cross section of the medical device or they can bepositioned at unequal intervals relative to the circumferential crosssection of the medical device.

In one embodiment, when engaged to a medical device, the athertomes 2are not in a rigidly radial deployed position and can change the anglethey form relative to the surface of the medical device. The athertomes2 can both self deploy and retract down on to the surface of the medicaldevice as needed through the expansion of the medical device or throughan independent expansion or retraction mechanism.

In embodiments having multiple athertomes 2, the athertomes may bepositioned in a uniform or non-uniform distribution about the medicaldevice. In some possible embodiments, different kinds of athertomes 2(including but not limited to athertomes known in the art, and/or thoseillustrated in FIGS. 1, 3, and 4) may be affixed to, may protrude from,or may be otherwise engaged to a medical device 5. Although FIGS. 2 and5 show the athertomes extending along the medical device in alongitudinal configuration, at least a portion of an athertome 2 canalso coil around the device in a helical configuration as shown in FIG.6, can extend around circumference of the device or can be positionedwith any combination of these configurations. In addition, the cuttingmember or members 7 need not be of uniform distance from the surface ofthe medical device 26 and differing portions of the cutting member 7 canbe closer or farther away from the surface of the medical device 5. Thecutting member 7 of the athertome 2 can taper downwards towards theterminal end 26 or downwards away from the terminal end 26. The cuttingmember 7 can also be serrated. This invention encompasses possibleembodiments where the athertomes are positioned along the medical devicein a fixed rigid position as well as embodiments where the athertomescan deploy and retract relative to the medical device.

Referring again to FIG. 1, there is shown a particular embodiment wheremost of the segments of the athertome 2 comprise at least one descendingmember 9 and at least one spanning member 15 between the cutting member7 and the base members 11. The spanning members 15 connect the basemembers 11 to the cutting member 7. Alongside the spanning members 15are descending members 9 which are connected to the cutting member 7 butnot the base members 11. The descending members 9 provide the cuttingsurface with additional support when the athertome 2 is used for cuttingbut because they are disconnected from the base members 11, they allowfor more flexibility than if they were rigidly connected. Although FIG.1 illustrates an embodiment where the segments are virtually identicaland regularly repeat, the invention is also directed to embodimentswhere the segments are not identical and the athertome 2 comprisessegments with different shapes and with different numbers of crossingmembers. In addition, the invention encompasses embodiments where someor even all of the base members 11 are interconnected or where some orall of the crossing members of segments are connected to the basemembers 11.

FIG. 1 illustrates one possible embodiment where the athertome 2 hasdescending members 9 and spanning members 15 which extend in a directionforming a 90 degree angle relative to the base members 11 and thecutting member 7. This invention however also encompasses embodimentswhere the spanning members 15 and the descending members 9 form obliqueangles relative to the cutting member 7, relative to the base members11, or relative to both. For purposes of this application the term“oblique” refers to an angle of between 0 and 180 degrees (according toan inclusive range) and explicitly includes angles of 30, 45, 60, and 90. . . etc. degrees. This invention also encompasses embodiments wherethe descending members 9, the spanning members 15, the through hole 14,the cutting member 7, and the base members 11 are not of a generallyrectangular shape.

Referring now to FIG. 3 there is shown another athertome 2 made up of aplurality of segments. In this embodiment, at least some of the segmentscomprise a spanning member 15 and a descending member 9 where thedescending member 9 is connected to the base member 11 by a connector20. The figure also has spanning members 15 defining both ends of theathertome 2. The descending member is substantially wider than theconnector 20. Unlike the embodiment of FIG. 1, a segment in thisembodiment has no descending gaps between the descending members and thebase members. Because of the difference in width between the connector20 and the descending member 9, this embodiment affords the athertomeflexibility but the connectors provide the athertome 2 with structuralstrength. Because a connected descending member 9 does not have as greata range of motion that an unconnected descending member 9 would, thisembodiment is not as flexible as the one illustrated in FIG. 1. However,because of the connections 20, this embodiment has greater structuralstrength than does the embodiment of FIG. 1. This embodimentcontemplates an athertome 2 in which some of the segments contain theattributes of the athertome as described in the descriptions of FIGS. 1,2, and 5.

The embodiment illustrated in FIG. 3 also has greater structuralstrength and less flexibility than the embodiment of FIG. 1 because ithas single base member 11. The flexibility and structural strength ofthis embodiment however can be modified by altering the nature of someor all of the athertome segments. The flexibility can be increased byhaving segments with multiple unconnected base members 11 and/orunconnected descending members 9. The base members can also be connectedby connectors with smaller widths than the widths of the base members11. This invention also encompasses embodiments where the descending andspanning members between the cutting member 7 and the base members 11 ofeach segments is non-uniform and irregular.

Referring now to FIG. 4 there is shown another athertome 2 made up of aplurality of segments. In this embodiment, at least some of the segmentscomprise two descending members 9 connected by a horizontal member 25.The horizontal member 25 is connected to the base member 11 by aconnector 20 and further defines the through hole 14. Although FIG. 4illustrates the connector 20 positioned at the center of the horizontalmember 25 this invention encompasses possible embodiments where theconnector 20 is positioned anywhere along the horizontal member 25.Because of the narrow width of the connector 20 relative to the width ofthe descending members 9, and because there is only one connector forevery two descending members 9, this design is highly flexible. Thehorizontal members 25 however provide this embodiment with structuralstrength.

The embodiments disclosed by the various drawings provide for athertomeswith a number of superior properties. The unconnected descending members9 and non-connecting base members 11 such as those illustrated in FIG. 1afford the athertome a wide range of motions resulting in a high degreeof flexibility. The improved flexibility allows for the athertomeundergo multidimensional bending. The multidimensional bend paths areillustrated in FIG. 5. They include bend paths along any possiblecombination of some or all of; the longitudinal axis 12, the transverseaxis 17 perpendicular to the longitudinal axis 12, and along thecircumferential arc 13.

This high degree of flexibility allows for a number of advantages to theathertome. Because it can bend to accommodate the tortuous curves ofbody vessels, the athertome can be more easily tracked through the body.This flexibility also allows the athertome to more easily pass throughor interact with other devices associated with a medical procedure (suchas passing through a guiding catheter). In addition, because theflexible athertome is less likely to straighten or otherwise deform bodyvessels such as arteries when being tracked through them, it is lesslikely to cause certain unwanted side effects. The improved flexibilityalso allows the athertome to be created with a greater thickness or outof a denser or harder material which would otherwise be too rigid to bepractical. The presence of a greater thickness or a denser or hardermaterial provides the athertome with an increase in cutting force.Finally, the greater flexibility allows for easier insertion and removalof the athertome as it can be moved, pulled, or pushed through a bodyvessel with less force.

In certain circumstances, an athertome with some flexibility, but withmore physical strength than that of FIG. 1 may be desired. The flexibleathertome of FIG. 4 is more rigid (and physically strong) than that ofFIG. 1 and the flexible athertome of FIG. 3 is more rigid (andphysically strong) than that of FIG. 4. The inventive conceptcontemplates embodiments where athertomes contain a combination of someor all of the features of FIGS. 1, 3, and 4. This resulting combinationcan be made to modulate the rigidity, strength, or flexibility of theathertome to a desired level and can cause a desired amount of rigidity,strength, or flexibility to be associated with an entire athertome or toa particular region of an athertome.

The athertomes illustrated in FIGS. 1-6 may be created by methodsincluding laser cutting, etching a design from a stock, cutting a flatsheet of material and stamping with a stamping die. These methods removethe excess material from the resulting athertome to form the base gaps,the descending gaps the through holes, and the open spaces between themembers and the segments as illustrated in FIGS. 1-5. By creating thesevarious openings and spaces, a very flexible but sufficiently strongathertome is provided. By increasing the loss of material (i.e. bymaking the members thinner and making the openings, spaces, and gapswider) a lighter more streamlined device can be provided. Theseathertomes can be created out of such materials including but notlimited to metals, polymers, carbon, and nanocomposites. Some specificexamples of materials used may include but are not limited tocopolymers, polyethylene terephthalate, nylons, polyamides, polyetherblock amides, thermoplastic polyester elastomers, polyethylenenaphthalate, and polyethylene naphthalate elastomers.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this art. The various elements shown in the individualfigures and described above may be combined or modified for combinationas desired. All these alternatives and variations are intended to beincluded within the scope of the claims where the term “comprising”means “including, but not limited to”.

Further, the particular features presented in the dependent claims canbe combined with each other in other manners within the scope of theinvention such that the invention should be recognized as alsospecifically directed to other embodiments having any other possiblecombination of the features of the dependent claims. For instance, forpurposes of claim publication, any dependent claim which follows shouldbe taken as alternatively written in a multiple dependent form from allprior claims which possess all antecedents referenced in such dependentclaim if such multiple dependent format is an accepted format within thejurisdiction (e.g. each claim depending directly from claim 1 should bealternatively taken as depending from all previous claims). Injurisdictions where multiple dependent claim formats are restricted, thefollowing dependent claims should each be also taken as alternativelywritten in each singly dependent claim format which creates a dependencyfrom a prior antecedent-possessing claim other than the specific claimlisted in such dependent claim below.

This completes the description of the invention. Those skilled in theart may recognize other equivalents to the specific embodiment describedherein which equivalents are intended to be encompassed by the claimsattached hereto.

1. A medical device assembly comprising: an expandable balloon having acentral longitudinal axis; and an athertome assembly disposed on theexpandable balloon, the athertome assembly comprising: at least onesegment having at least one base member and at least one cutting member,the culling member having a first and a second side, at least a portionof the first side having a cutting surface, the at least one segmentfurther having at least one descending member and at least one spanningmember, a through hole being at least partially defined between the atleast one descending member and the at least one spanning member; the atleast one spanning member engaged at one end to the second side of theat least one cutting member and engaged at another end to the at leastone base member; and the at least one descending member engaged at oneend to the second side of the at least one cutting member and extendingin the direction of the at least one base member but not being engagedto the at least one base member; wherein an imaginary planeperpendicular to the central longitudinal axis passes through thecutting member, the base member and the at least one descending member.2. The medical device assembly of claim 1 in which more than one segmentshare an uninterrupted cutting surface extending along the length of theathertome assembly.
 3. The medical device assembly of claim 1 in whichthe base members of at least two adjacent segments are not immediatelyadjacent.
 4. The medical device assembly of claim 1 in which the basemembers of at least two adjacent segments are engaged to each other anddefine an uninterrupted base member.
 5. The medical device assembly ofclaim 1 further comprising at least one connector connecting the atleast one descending member to at the least one base member, the atleast one connector having a width substantially narrower than a widthof the at least one descending member.
 6. The medical device assembly ofclaim 1 in which the athertome assembly has two ends, at least one enddefined by the at least one spanning member.
 7. The medical deviceassembly of claim 1, in which the at least one segment further comprisestwo adjacent descending members each engaged to a horizontal memberextending between the two descending members, the horizontal memberfurther defines the through hole, the horizontal member being connectedto the base member only by a connector, the connector having a widththat is substantially narrower than a width of either of the twodescending members.
 8. The medical device assembly of claim 7 in whichthe connector is in the center of the horizontal member.
 9. A medicaldevice assembly comprising: an expandable balloon having a centrallongitudinal axis; and an athertome assembly disposed on the expandableballoon, the athertome assembly comprising: at least one segment havingat least one base member and at least one cutting member, the cuttingmember having a first and a second side, at least a portion of the firstside having a cutting surface, the at least one segment comprising aplurality of descending members and a plurality of spanning members, thedescending members and spanning members alternatingly positioned with athrough hole being at least partially defined between each descendingmember and spanning member; the spanning members engaged at one end tothe second side of the at least one cutting member and engaged atanother end to the at least one base member; and the descending membersengaged at one end to the second side of the at least one cutting memberand extending in the direction of the at least one base member but notbeing engaged to the at least one base member; wherein an imaginaryplane perpendicular to the central longitudinal axis passes through thecutting member, the base member and at least one descending member. 10.A medical system comprising at least one athertome assembly and at leastone medical device having a central longitudinal axis, the at least onemedical device being selected from at least one member of the groupconsisting of a stent, a catheter, a balloon, a sheath, a graft and anycombination thereof, the athertome assembly comprising at least onesegment having at least one base member and at least one cutting member,the cutting member having a first and a second side, at least a portionof the first side having a cutting surface, the at least one segmentfurther having at least one descending member and at least one spanningmember, a through hole being at least partially defined between the atleast one descending member and the at least one spanning member; the atleast one spanning member engaged at one end to the second side of theat least one cutting member and engaged at another end to the at leastone base member; the at least one descending member engaged at one endto the second side of the at least one cutting member and extending inthe direction of the at least one base member but not being engaged tothe at least one base member; and the at least one base member beingengaged to a surface of the at least one medical device; wherein animaginary plane perpendicular to the central longitudinal axis passesthrough the cutting member, the base member and the at least onedescending member.
 11. The medical system of claim 10 in which there arebetween three and four athertome assemblies engaged to the at least onemedical device.
 12. The medical system of claim 10 in which there ismore than one athertome assembly, where the at least one medical devicehas a cross sectional circumference and where at least two athertomeassemblies are located at positions substantially equidistant from eachother relative to the cross sectional circumference.
 13. The medicalsystem of claim 10 in which there is more than one athertome assembly,where the at least one medical device comprises a terminal end, andwhere at least two athertome assemblies are positioned at differentdistances relative to the terminal end.
 14. The medical system of claim10 in which at least a portion of at the least one athertome assemblyextends along the surface of the at least one medical device in alongitudinal direction.
 15. The medical system of claim 10 in which atleast a portion of the at least one athertome assembly is coiled aroundthe at least one medical device in a helical direction.
 16. The medicalsystem of claim 10 in which the distance between the surface of the atleast one medical device and the adjacent cutting surface of the atleast one athertome assembly at one point along the length of the atleast one athertome assembly is different from the distance between thesurface of the at least one medical device and the adjacent cuttingsurface of the at least one athertome assembly at another point alongthe length of the at least one athertome assembly.
 17. The medicalsystem of claim 16 in which the at least one medical device has aterminal end and in which the at least one cutting surface at the end ofthe at least one athertome assembly closer to the terminal end is closerto the surface of the at least one medical device than the at least onecutting surface at the end of the at least one athertome assemblypositioned farther away from the terminal end.
 18. The medical system ofclaim 16 in which the at least one medical device has a terminal end andin which the at least one cutting surface at the end of the at least oneathertome assembly closer to the terminal end is farther away from thesurface of the at least one medical device than the at least one cuttingsurface at the end of the at least one athertome assembly positionedfarther away from the terminal end.
 19. The medical system of claim 10in which the angle formed between the at least one athertome assemblyand the surface of the medical device can change.
 20. A medical deviceassembly comprising: an expandable balloon having a central longitudinalaxis; and an athertome assembly disposed on the expandable balloon, theathertome assembly comprising: a) first segment comprising: i) a basemember; ii) a cutting member, the cutting member having a first side anda second side, at least a portion of the first side having a cuttingsurface; iii) a spanning member engaged at one end to the second side ofthe cutting member and engaged at another end to the base member; iv) adescending member engaged at one end to the second side of the cuttingmember and extending in the direction of the base member but not beingengaged to the base member, wherein an imaginary plane perpendicular tothe central longitudinal axis passes through the cutting member, thebase member and the descending member; and v) a through hole being atleast partially defined between the descending member and the spanningmember; and b) a second segment comprising: i) a base member; ii) acutting member, the cutting member having a first side and a secondside, at least a portion of the first side having a cutting surface;iii) a spanning member engaged at one end to the second side of thecutting member and engaged at another end to the base member; iv) adescending member engaged at one end to the second side of the cuttingmember and extending in the direction of the base member but not beingengaged to the base member, wherein an imaginary plane perpendicular tothe central longitudinal axis passes through the cutting member, thebase member and the descending member; and v) a through hole being atleast partially defined between the descending member and the spanningmember; wherein the cutting member of the first segment is continuouswith the cutting member of the second segment.
 21. The medical deviceassembly of claim 20, wherein the base member of the first segment isdiscontinuous with the base member of the second segment, defining a gapbetween the base member of the first segment and the base member of thesecond segment.
 22. The medical device assembly of claim 20, wherein thecutting surface of the cutting member of the first segment and thecutting surface of the cutting member of the second segment form acontinuous and uninterrupted cutting surface.